Behavior of AUTO DEVOPS BUILD IMAGE EXTRA ARGS set within a group and its projects

I set the CI environment variable AUTO_DEVOPS_BUILD_IMAGE_EXTRA_ARGS in a group and also set the same environment variable in a project within the group.

In this case, does the AUTO_DEVOPS_BUILD_IMAGE_EXTRA_ARGS in the project completely replace the environment variable in the group? Or does it apply the build arg of the project in addition to the build arg in the group?